Cyndane is still stronger than Graendal, who is much, much stronger than Moiraine, and stronger than even Nynaeve.

Most people are of the opinion that this sort of thing is way beyond the Finns's abilities anyway (hopefully, TOM and the TOG episode will clarify a lot of those questions). Jordan made a point that their powers are limited and not "god like", and a lot of people are of the opinion that even a godly being like Shai'tan can't really alter someone's ability to channel (ie: he can't give boosts, and he can't reduce the ability for real, that it will turn out Cyndane's strength was reduced almost symbolically by a partial TP shield to punish her for what she did to Asmodean).